Wind Turbine Mainshaft Radial Load
Wind Turbine Mainshaft Radial Load
(OP)
I'm currently looking at the loads subjected on the Main Bearing in a Wind Turbine. I have completed the calculations as per IEC 61400. This has allowed me to calculate the Axial load, Bending moment and torque of the shaft.
I have to calculate the Radial Load, which I have done using the equation RL = Torque/Shaft Radius. However the figure I am equating is a radial load of 3MN, which seems far to high.
Is this the correct equation to use?
If not, what should I be doing?
I have to calculate the Radial Load, which I have done using the equation RL = Torque/Shaft Radius. However the figure I am equating is a radial load of 3MN, which seems far to high.
Is this the correct equation to use?
If not, what should I be doing?





RE: Wind Turbine Mainshaft Radial Load
i suspect torque of the shaft is the torque created by the blades of the wind-mill which would be reacted by the torque required to drive the generator at the other end of the shaft.
radial load as i see it would have something to do with the gyroscopic effects of the spinning blades, and an off-axis wind condition.
RE: Wind Turbine Mainshaft Radial Load
calculated as;
(rated power x 30)/(rotor speed x pi x 0.8)
where Power = 1500x10^3 watts and Rotor speed = 20.5 r/min
=> Torque = 873411.27 Nm
My understanding is to convert this to Radial Load, I would use;
T = radius x load => Load = T/radius.
If my shaft radius is 0.285m
This equates to Radial load of 3.06 MN.
Which I feel is incorrect. Therefore I suspect I'm using the wrong equation.
RE: Wind Turbine Mainshaft Radial Load
won't the torque travel along the shaft from the prop plane to the generator ?
RE: Wind Turbine Mainshaft Radial Load
Torque = F x r
where the bold indicates vectors, and x is the vector cross product.
Dunno how you would create a moment (torque) with a radially directed force...a tangentially directed force on the other hand...
RE: Wind Turbine Mainshaft Radial Load
RE: Wind Turbine Mainshaft Radial Load
The question I posed is a small part of a far larger project.
RE: Wind Turbine Mainshaft Radial Load
you could be a student, working, like a co-op, asking a question from the real world ... just doesn't look like it.
i note that you haven't answered the question, why react the prop torque at the side of the shaft (unless you're applying a brake) ?
RE: Wind Turbine Mainshaft Radial Load
The main bearing is positioned approx. 1 metre from the rotor, and is subjected to loads caused by the Rotor. Those being axial, and radial.
The stalling point I have is working out the Radial load on the bearing.
I may have a major misunderstanding with the relationship between Torque and Load, which I expressed earlier.
RE: Wind Turbine Mainshaft Radial Load
There are two conditions contributing to a radial load. The first is the static moment and load of the rotor, which is hanging on a shaft 1 meter from the main bearing. Simple beam equations will suffice to find those loads.
The second condition effecting radial loading is shaft deflection and/or rotor imbalance; as the center of mass of the rotor shifts away from an ideal central rotation axis, there will be axial loading equal to m*r*(rotation speed)^2, where r is the distance from the COM to the center of rotation and m is the rotor mass.
I think that is what you are looking for. Shaft torque does not load the bearing significantly, as long as the bearing is in working order.
RE: Wind Turbine Mainshaft Radial Load
RE: Wind Turbine Mainshaft Radial Load
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RE: Wind Turbine Mainshaft Radial Load
RE: Wind Turbine Mainshaft Radial Load
Regards,
Mike
RE: Wind Turbine Mainshaft Radial Load
RE: Wind Turbine Mainshaft Radial Load
I would assume your HAWT drivetrain is the typical 3 point mount with the fwd rotor shaft bearing being a duplex spherical roller and the aft bearing being a pair of cylindrical rollers supporting the primary planetary stage carrier within the gearbox. And the rotor shaft would be rigidly coupled to the gearbox primary stage planet carrier using a hydraulic shrink coupling, and the gearbox housing is mounted on a pair of horizontal trunnion shafts.
In this case, the only significant source of radial load on the forward rotor shaft bearing is the mass of the rotor hub, shaft and blades. On a typical 1.5MW utility scale turbine, these components' combined weight can easily exceed 30 tons.
The forward duplex spherical roller bearing also would be subject to axial loads, due to the blade thrust forces. However, by far the most significant forces the rotor shaft bearings are subject to are the out-of-plane rotor moments, due to variations in wind velocity across the rotor disc creating asymmetric blade lifts.
Here's a good reference on HAWT rotor shaft bearings: http://
Hope that helps.
Terry